Although this condition is rare, it is possible in a few circumstances. Most often, it is due to a pending invoice payment that has already been entered in QuickBooks. When the sync software attempts to apply the payment, it is unable to as the invoice has a zero balance.
There are a couple ways to resolve this.
Customer that won't sync:
In most cases, this can easily be fixed by just making some small change to the customer record and then run your sync again. The change to the record will trigger it to be re-synchronized to the portal. Also, be sure you have actually enabled the customer in the portal. The customer may have already been synchronized to the portal but has not been enabled yet. From the "Customers" menu, click "Enabled/Disabled Customers".
Payments that won't sync:
If it is a payment record that will not sync to QuickBooks and you can confirm that the payment has already been recorded in QuickBooks, you simply need to manually "purge" or remove the stale record from the portal. You will need Admin permissions to perform this task. Under the Billing menu, there is a menu called "Remove Records". Click "Remove Records", and then "Payments". Enter part of the customer name to locate the stale payment record. Use the "Remove" button to remove the stale record. Be careful when using this method. Be certain you are removing the correct record. Missing records CAN be fixed, but it's best to avoid having to use that procedure.
Invoice that won't sync:
In most cases, this can easily be fixed by just making some small change to the invoice record and then run your sync again. The change to the record will trigger it to be re-synchronized to the portal.
If you are using QuickBooks Desktop Edition, also check that the invoice is not marked as "pending".
How to force a QuickBooks Desktop record to re-sync
If you are still having a problem getting one or more records to sync, please contact us by email or chat and we can help you clear it out.